We typically use 3 properties to describe a core:  RG, Total Diff and Intermediate Diff.

so, assuming similar/same cover stocks, should we expect all cores that measure to 2.48 RG, 0.054 Diff and 0.018 intermediate diff to react the same? 

Or does the shape of the core matter?  We have all sorts of different shapes that measure to the same RGs, and same or very near the same diff. 

what I am curious to know, if I was replacing an old favorite.  perhaps my Big Time Pearl or Paradigm Domination and was looking for a similar core to one of those, is it really as simple as finding a ball with a core with the same measurables?  it seems to reason that shape would matter as well.  if only for the likely impact of being drilled into by the finger/thumb holes.

Core shape dictates motion. A tall core with a high RG isn't going to react the same as a light bulb core with the sake numbers.

A little too much sake can really throw off the numbers.

Yes, taller cares can, in general, impart a flippier motion than can more round shaped cores. Flippier does not  mean flippy; it just means a tall, thin core can allow a ball to have a backend than can be sharper than the core with a more round type of shape. Too many other factors also influence the ball shape, like the bowler's release and the surface and the amount/pattern of the oil.